I learned thanks to Javier Santaolalla that Aristarco de Samos, a Greek philosopher, astronomer and mathematician, was the first person to propose the first Heliocentric model that places the Sun in the center of the known universe and not the Earth.

This theory is commonly known that Galileo was who developed even though this knowledge comes from old Greek. He just gave mathematical evidence in the form of calculations/experimentation while Aristarco gave some calculations but his work is more focused to phylosophy.